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(No Model.) 2 Sheets-Sheet 1.

G. W. DREW 8: E. R. FRANCIS.

ELECTRIC HEATER.

No. 454,979. Patented June 30,1891.

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G. W. DREW 8v E. R. FRANCIS. ELECTRIC HEATER.

No. 454,979. Patented June 30,1891.

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UNITED STATES PATENT OFFICE.

CHARLES \V. DRElV AND EDlYARD R. FRANCIS, OF MINNEAPOLIS, MINNE- SOTA; SAID FRANCIS ASSIGNOR TO SAID DREW.

ELECTRIC HEATER.

SPECIFICATION forming part of Letters Patent No. 454,979, dated June 30, 1891.

Application filed February 20, 1890. Renewed December 1, 1890. Serial Nb. 373,181. (No model.)

T at whom it may concern:

Be it known that we, CHARLES 1V. DREW and EDWARD R. FRANCIS, both of Minneapolis, in the county of IIennepin and State of 5 Minnesota, have invented certain Improvements in Electric Heaters, of which the following is a specification.

The object of this invention is to provide an improved means for utilizing an electric current for heating purposes; and theinvention consists in providing a heater of this class with a rheostatic device arranged in and forming a part of the heater, so that whatever heat is generated by the passage of the I 5 current through the rheostatis utilized in the heater, and with means whereby the current may be madeto pass through any number of the resistant-coils of the rheostat, so that the heat generated by the passage of the current zo through the resistance arranged in proximity to the heating-surface may be regulated.

The invention consists, further, in the construction and combination hereinafter described, and particularly pointed out in the claims.

In the drawings, Figure 1 is a plan view of our heater, partly broken away to show the arrangement beneath of the rheostatic coils. Fig. 2 is a transverse section on line 00 a of Fig. 1. Fig. 3 is a plan showing the arrangement of the rheostatic coils. Figs. at, 5, (3, 7, and 8 are details.

In the drawings, 2 represents a suitable casing provided, preferably, with a lining or 3 5 base 3 of electric insulating and non-heatconducting material. This casing is provided with a suitable cover or heating plate or surface 5, that is secured thereto in any suitable manner, preferably forming with said casing an air-tight receptacle. Arranged beneath said heating-plate, and preferably only a short distance therefrom, is a suitable electric resistance, through which an electric current may be passed, thereby causing heat to be radiated. from said resistance, and thus to heat said plate or surface. This electric resistance may be in the form of carbon or graphitized rods or sticks 7, that are supported in suitable electric conductors 9: insulated from each other and connecting said carbon; or it may consist of suitable wires or strips 11 of suitable resistance metal or material wound upon suit-able rods 13, consisting of insulating material or covered or coated with such material, and secured to the base 3; by means of supports 12; or both forms of resistance may be used in the same heater, as shown in Fig. 1. Arranged within said casing and below said resistance is a rheostatic device by means of which the current pass ing through the resistance next the heatingplate may be regulated. This rheostat consists of a series of electrical resistances that are coupled together and connected to a suitable switch, so that the current may be caused to pass through any desired number of coils composing said rheostat, whereby the current supplied to the upper or heating resistance may be regulated, thus makingit practicable to employ currents of greater intensity than could otherwise be made use of, and regulating the heat generated by the heaters, and at the same time utilizing whatever heat is generated in the rheostat. The rheostat consists, preferably, of a series of electric resistance coils or wires 15, that are arranged on rodsllT or strips of electrical insulating material, or rods covered or coated with electrical insulating material. These coils are preferably arranged in pairs, and an electric conductor 21 extends from each pair to an insulated switch-plate 23. A switch 25, (shown in dotted lines,) having one end connected to the upper or heating resistance, is adapted to be brought into contact with any one of the plates 23, thereby forming a short circuit and cutting out a portion of the rheostat. hen the switch is on the first plate 23, the rheostat is entirely cut out. \Vhen it is on the second plate, two of the coils are in use. \Vhen it is on the fourth plate, four of the coils are in use, and so on. By this means any portion or all of the rheostatic resistance maybe brought into service, and thereby the supply of current to the heating-resistancc regulated.

Any suitable rhcostatic resistance may be used. Carbon rod may be used in place of the rheostatie coil, if preferred, it being adapted in a like manner to be operated with I00 a switch. Any suitable resistancemay also be used next to the he:;1.ting-plate.

We claim as our invention- 1. In an electric heater, the combination, with a suitable casing, of an electric heatingresistanee arranged therein, a rheostat also arranged within said casing and connected with said heating-resistance, and a switch whereby any number or all of the coils of the rheostat may be cut out.

2. In an electric heater, the combination, with a suitable casing, of an electric heatingresistance arranged therein, a heating-plate arranged over said heating-resistance, a rheostat arranged in said casing beneath said heating-resistance and connected therewith, and a switch whereby any portion of said rheostat may be cut out, substantially as described. 

